"In coordination with the Lebanese Red Cross, we have transported some 40 wounded."

The al-Hosn area is home to the famed Krak des Chevaliers, one of the Middle East's best preserved Crusader castles. But the UNESCO World Heritage site suffered mortar hits last year when rebels hid behind its thick stone walls, built for battles hundreds of years ago.

The Syrian army bombarded rebel positions near the castle on Wednesday. And on Thursday the army said it killed 11 rebels as they fled al-Hosn for Lebanese border.

"During the operations in the al-Hosn area, armed men (rebels) tried to flee for Lebanese territory. They fell to an ambush laid by the army, and 11 armed men were killed," a military source told AFP.

Meanwhile protesters cut off a major road near Halba in northern Lebanon to protest the shelling, the NNA said.

And in the northern city of Tripoli, dozens of followers of an influential sheikh Salem al-Rifai gathered outside the Salam mosque in solidarity with the Akkar.

Elsewhere in restive Akkar, clashes continued for an eighth straight day between residents of rival neighborhoods divided over the war in Syria.

In Syria, the al-Hosn offensive is one of two major operations by the Syrian army close to the border aimed at denying rebels supply routes for weapons.

Troops and fighters with Hezbollah have also been engaged in a major offensive since November in the Qalamoun mountains north of Damascus, where they recaptured the last major rebel stronghold Yabrud on Sunday.

The advances brought the Syrian government forces right up to Lebanon's eastern border, where air raids hit the Ersal area late on Wednesday.

The strikes, which may have been targeting fleeing rebels, caused no casualties, an official told AFP on condition of anonymity.

"Syrian helicopters carried out two strikes against the areas of Wadi Ajram and Khirbet Younine, on the outskirts of Ersal, just after 9:00 pm (1900 GMT)," he said.

The area, which hosts tens of thousands of Syrian refugees, has been hit by repeated cross-border fire in recent months, some of it deadly.

Smuggling routes used by opposition forces to move fighters and weapons back and forth between Lebanon and Syria pass through the Ersal area.

On Wednesday, the Lebanese army arrested 15 Syrian men at an Ersal checkpoint, the National News Agency reported.

"The men had entered Lebanese territory with forged papers, and some of them were members of (Al-Qaeda's Syria affiliate) Al-Nusra Front," it said.